The present invention relates to a sheet finisher that receives a sheet coming from an image forming apparatus, then, conducts sheet finishing on the sheet and feeds out the sheet and to an image forming system characterized to have the sheet finisher and an image forming apparatus that feeds a sheet into the sheet finisher, and in particular, to a sheet finisher having a stacking section that is arranged obliquely from the horizontal direction and stores one or more sheets temporarily and an image forming system.
With respect to the aforesaid stacking section that is arranged obliquely from the horizontal direction, it is aslant so that an empty weight of the sheet causes the sheet to slip down along a stacking surface to stop at a prescribed position, when a sheet is fed into it. In a circumference of the stacking section, there are arranged sheet finishing sections that conduct sheet finishing for the sheets stored in the stacking section.
The sheet finishing section includes a stapling section that staples a sheet bundle, a folding section that conducts center-folding for a sheet bundle or folds each sheet in three, an aligning section that aligns sheet bundles in a width direction or in a conveyance direction, or a punching section that punches a hole for a sheet bundle.
Further, on the stacking section, there is also arranged a positioning regulating member that moves a sheet vertically to position for conducting processing for a sheet at a determined position in the aforesaid sheet finishing section.
Since the stacking section of this kind is arranged obliquely, there is sometimes an occasion of buckling that sheets stored in the stacking section buckle, namely, the sheets are bent and do not line up straight on the stacking surface. If the sheets do not line up due to the buckling, it is impossible to conduct sheet finishing on the lined up sheet bundle because of slippage of sheets, in the case of processing carried out by a sheet finishing device arranged on the stacking section. The bucking of this kind takes place frequently on the lower side portion of sheets where each of the sheets receives its own weight, in particular.
In the past, there has been a construction having the structure wherein an elastic sheet such as PET is arranged on an inside of the stacking section, to press the sheet that has been fed into against the stacking surface, to prevent the buckling of this kind. However, when the number of sheets stored grows greater, elastic sheets that press the sheet become resistance against sheet conveyance, and there have been troubles that the sheet is not conveyed to the prescribed position to cause slippage.
In the technology disclosed in Unexamined Japanese Patent Application Publication No. 2004-83261, there are provided a tapping roller that aligns sheets by applying a pendulum motion on the stacking surface and a pressing roller that presses a sheet bundle by swinging from a standing by position to an operation position, for preventing the buckling of the sheet. In the constitution of this technology, the tapping roller aligns sheets in the conveyance direction by applying a pendulum motion for each sheet carried in, and after that, the pressing roller presses a bundle of sheets in the direction of the sheet.
The technology disclosed in the aforesaid Unexamined Japanese Patent Application Publication No. 2004-83261 is complicated in terms of the construction, to cause cost increase, which is a defect. In addition, the construction needs to be provided in the vicinity of the position for sheet carry-in for aligning sheets by a pendulum motion, which further requires more space, resulting in a restriction of a position of installation for acquiring a space.